Frequency converting means



F. M. BAILEY FREQUENCY CONVERTING MEANS Feb. 1s, 1947.

Filed' oct. 8, 1942 y, w he ,n W, im e d A Y@ f. Tm n H m. w a v Q s PNN m o m, mm mq m JQ we, mw Q my, \\}|\W\\\x .Q ww Q Mw w 8 mh mv 3 5 N mi 85.363 1mm. om N, :and QL wm. 0. O N a Y c s mm l a \\\\\x i b s .MVMW O w G 2 Feb 18, 1947 F. M.BA1| EY FREQUENCY CONVERTING MEANS Filed Dot. 8, 1942 3 Sheets-Sheet 2 till/11111110 INPUT Pnoas y3a Inventor: F`T`emc$ M. Baile END EFFECT but ro DISCHARGE mzvlc: 6

His Attorney Feb. 18, 1947. F M BAILEY FREQUENCY CONVERTING MEANS Filed oct. 8, 1942 s sheets-sheet 3 RESISTANCE c, B 2

6l DEGREES T0 Locm. 75 osclLLATon 77 Inventorv `Francis M. Bailey.v by .3V

` His Attorney.

Patented Feb. 18, 1947 FREQUENCY CONVERTING MEANS.

Francis M. Bailey, Scotia, YI., assigner to Gen` eral Electric Company,

York

a corporation of' New Application October, 194.2, Serial N0.v 461,295 v 61 Claims. l. 1 I My invention relates to ultra high frequency apparatus and more particularly to electrical apparatus of the space resonant type, such as concentric transmission lines and dielectric wave guides of the hollow-pipe type and control apparatus therefor.

It is an object of my invention to provide new and improved ultra high frequency apparatus.

It is another object of my invention to provide new and improved ultra high frequency conversion or frequency changing apparatus.

It is a further object of my invention to provide new and improved frequency changing or conversion apparatus of the space resonant type.

It is a still further object of my invention to Aprovide new and improved conversion apparatus comprising a section, or sections, of a dielectric wave guide of the hollow-pipe type.

It is a still further object of my invention to provide new and improved high frequency conversion apparatus of the space resonant type wherein greater power and power conversion ra- .tios are obtained than those afforded by the prior art arrangements.

It is a still further object of my invention to provide new and improved arrangements for matching the impedances of ultra high frequency .space resonant devices to the impedances of asyprovide new and improved methods of tuning ultra high frequency conversion apparatus such as frequency changers and the like.

.Briefly stated, in the illustrated embodiments of my invention I provide new and improved ultra high frequency apparatus for the transmission of electromagnetic waves now commonly referred to as microwaves More particularly, I provide new and improved control or adjusting equipment whereby space resonant devices may be tuned or matched in impedance to associated equipment, such as a coaxial transmission line.

Means are provided not only for controlling the` resistive component of the space resonant cavity -or region of the devices, but means is also pro- 'gvided for adjusting the reactive component so that the impedance of the cavity or region, as

Vviewed from input electrode means, may be made equal to, that is matched to, the impedance of .the apparatus connected to the input electrode means. In this manner, maximum power transfer between associated equipmentand the'spa'ce resonant device,.or devices, is obtained. In accordance with a further feature of'my invention, I provide newand improved frequency changing or conversion apparatus of the space resonant type'which permits new design and utilization of space resonant devices having a space resonant cavity or region which is tuned to be resonant not only to the frequency of the input `signal but is also resonant to the intermediate frequency. More particularly, the region or cav- 1 ity may be adjusted in its length,or other dimen.. sion, so that the cavity comprises an odd multiple of quarter-wavelengths of the input signal and at the same time the cavityor region is made resonant to the intermediate frequency by choosing the length so that it is also an odd multiple `of a quarter-wave length of the intermediate frequency. In such an arrangement, of course, the fact that the cavity or region is not resonant to the frequency' of thelocal oscillator excitation is lnot disturbing, inasmuch as sufficient power, as a.

general rule, may be supplied to establish suit,- able local oscillator excitation vwithin the cavity.

The high frequency conversion or frequency changing apparatus may be constructed to have Aa pair of space resonant cavities or regions associated with the cathode-gridv and the grid'- Aanode circuit of an associatedelectric discharge device, The cathode-grid cavity may be designed to be resonant to two frequencies, that isthe local yoscillator frequency and the input frequency, and the grid-anode cavity may be tuned to be resonant to the intermediate or output frequency.

My invention may also be applied to conversion apparatus using a dielectric wave guide ofthe hollow-pipe type wherein a section of the guide is designed to form a space resonant region, Ythe guide being excited either by radiation from the ether or by input electrode means. An excitation of different frequency, which may-be constant, is also established within the guide and vthe resultant or difference of the two frequencies .may be employed to modulate the electric discharge between an anode and a cathode of 'an -enclosed electric discharge device which is positioned within` the wave guide. In such a case,

where the cathode and the grid are connected to ,.oppositely .disposed walls of the guide, the electric discharge is modulated in accordance with the instantaneous values of the two electromagnetic waves within the guide and the intermediate frequency energy so produced may be extracted .by a utilization circuit connected to the anode of ,the discharge device. l also provide in systems of this nature means for tuning or matching the impedance of the input electrode means, and also provide means for tuning or adjusting the dimensions of the cavity so that it is resonant to electromagnetic waves of predetermined frequency. Furthermore, I provide means for neutralizing the reflection incident to the presence of the electric discharge device within the cavity. This means may comprise a stub adjustable along the longitudinal axis of the guide.

In accordance with a still further feature of my invention, I provide new and improved conversion system for ultra high frequency electromagnetic waves which comprises a dielectric wave guide of the hollow-pipe type through which 'electromagnetic waves of predetermined frequency may be transmitted along the longitudinal or principal axis of the guide. A second electromagnetic wave, such as a constant frequency wave derived from a local oscillator, may also be established within the guide, and the lresultant or difference of the two waves is employed to modulate or control the electric discharge of a device positioned within the guide. In this instance, the transverse dimension of the guide may be chosen to be a multiple of a half-wave length of the difference frequency so that the guide is transversely tuned to the difference frequency; and energy may be extracted from the guide by use of means lying within the vicinity of the electric discharge device, or in a plane transverse to the longitudinal axis. The electric discharge device is preferably positioned at a point within the vicinityr of the potential maximum of the transverse potential wave.

l For a better understanding of my invention, reference may be had to the following description taken in connection with the accompanying drawings, and its scope will be pointed out in the appended claims. Figs. 1 andl 2 diagrammatically illustrate cross sectional top and side views of ultra high frequency conversion apparatus of the space resonant type embodying my invention, and Fig. 3 is a cross section detail View of one type of electric discharge device which may be employed as a central element of the space resonant system. Fig. 2a is an equivalent circuit repreillustrates certain operating characteristics of the device shown in Figs. 1 and 2; Fig. 5 is a further modification of my invention wherein two tuned space resonant cavities are employed; Figs. 6 and '7 are cross sectional and perspective views of an application of my invention to a dielectric wave guide of the hollow-pipe type; Fig. 8 is a modification of the arrangement shown in Fig. 6 wherein a tuned space resonant system is employed for extracting energy from the grid-anode circuit ofthe electric discharge device and which is tuned to the intermediate frequency; and Figs. 9 and 10 diagrammatically illustrate a still further embodiment of my invention which mayA be applied to a, frequency changer or converter wherein the dielectric wave guide is designed to be resonant in the transverse dimension to the difference or intermediate frequency.

Referring now to Figs. 1 and 2, considered jointly, which are cross sectional top and side views, I have there illustrated my invention diagrammatically as applied to anultra high frequency space resonant system for the conversion of electromagnetic waves of a Wave length within the region of 1 to 20 centimeters, or less. The apparatus there illustrated maybe mountedV upon 'the interior surface ofl cylinder 4.

a bedplate I comprising a pair of vertical supporting members 2 and 3 which support the conductive structure of a space resonant system. I provide a pair of conductive or metallic members, such as metal cylinders 4 and 5 preferably constructed of copper or brass, which denne a space resonant cavity or region, the particular characteristics of which will be described presently. The outer surface of cylinder 5 may be plated with silver to facilitate sliding engagement thereon of the input electrode means described hereinafter. The cylinders 4 and 5 may be coaxial, defining therebetween the above mentioned space resonant region, and cylinder 4 may extend through openings provided in the supporting members 2 and 3. An electric discharge device 6,

'represented in detail in Fig. 3, may be employed as the central element of the space resonant system and may be supported in the position illustrated by means of a fixed annular collar 'l on v An insulating ring 8 is maintained in engagement with the socket 9 for the discharge device 6 by a threaded cap Iii which is screwed into the end of cylinder 4. The end wall of cap Ill may be provided with an opening II and a suitable insulator I2 to permit external access to the electrodes of discharge device 6 through the socket 9.

It is believed that it will be helpful, prior to further description of the space resonant system as a Whole, to describe the discharge device 6 illustrated in Fig. 3. Referring to Fig. 3, there is shown an electric discharge device of the ultra high frequency type comprising a cylindrical anode I3, a grid I 4 and a cylindrical cathode I5 having its emissive part in form of a flat disc surface IB which faces the grid I4. The envelope within which these electrodes are mounted comprises a series of three circular metal parts I'l, I8 and I9 which are supported in mutually spaced relation by glass cylinders 20 and 2l which are sealed between parts I'! and I8, and I8 and I3, respectively. The part I 8 provides a terminal for grid I4 and a terminal for the anode is provided by a cylindrical extension 22 of the anode I3.

Cathode I5 is provided at its lower extremity with a, fiange 23 which parallels the under-surface of part I9 but which is separated from that part by an insulating spacer 24 which may be a mica washer. With this arrangement, the part I9 has a high frequency connection with the cathode through the capacity existing between this part and flange 23, but is effectively insulated from the cathode as far as direct current is concerned. Separate direct current connections are made to the cathode by means of lead-in wires 2-5 secured to the under-surface of fiange 23 and terminally connected to prongs 26 which depend from the base ofthe discharge device. Additional prongs 2l and lead-in wires 28 are provided for the purpose of supplying heating current to a coiled filament 2S arranged within the cathode cylinder I5, so that the emissive part of the filament can be maintained at an elevated temperature by this means.

In the arrangement of Figs. 1 and 2, the electric discharge device B is seated in a socket arrangement, described above, comprising the rings 'I'. A

cathode connection to cylinder 4 may be obtained by means of an annular resilient collar 30 comprising a plurality of fingers which may be welded or soldered to cylinder 4 and which serves to maintain the discharge device 6 firmly in position. In like manner, the connection of the grid part I8 to the inner cylinder 5 may be obtained by means of a plurality of metallic fingers 3| which may be of a construction to afford suitable resilience and may be welded to cylinder 5.

I employ an anode adapter comprising a metallic block 32 of cylindrical form, preferably constructed of copper or brass, lwhich is supported by an anode rod connection 33 and which is provided with a central opening which extends around the cylindrical anode portion 22 of discharge device 9, thereby affording an electrical connection thereto. If desired, a further supporting and engagement member 34 of resilient construction may be employed and may comprise 'a plurality of metallic ngers engaging the plate lor part I1. The anode connection rod 33 may be supported at its right-hand extremity by means of an insulating spacer 35, and rod 33 may extend therethrough and serve as a connection to the output or utilization circuit to be described hereinafter.

In accordance with my invention, I provide means for controlling or adjusting the impedance of the space resonant cavity or region dei-ined by the cylinders 4 and 5. More particularly, I provide means for matching the impedance of this region,

which may be defined as the cathode-grid region, to the impedance of associated apparatus or equipment, such Ias a concentric transmission line comprising an outer conductor 36 and an inner conductor 31 which are connected to input electrode means for the cathode-grid cavity. The

'input electrode means is adjustable or controllable space relation by means of insulating ring 4U, and

the entire assembly may be mounted upon an adjustable base plate 4| supported by cylinder 4. It will be noted that the input electrode assembly, and particularly the probe 38 and collar 42, extend through a longitudinal opening 43 in the outer "cylinder 4 so that the finger 39 may be moved appreciable distances longitudinally along the cylinder 5 to effect the desired range of tuning. l

As a means for providing a metallic end wall for the space resonant region, I employ a conductive or metallic plunger 44, preferably of annular configuration, which is adjustable along the axial length of the space resonant system and is in physical contact with the inner surface of the outer cylinder 4 and the outer surface of inner l vcylinder 5. As a means for adjusting the position of plunger 44, I may use any mechanical expedient and have chosen to employ a pair of rods `45` and 4B, respectively, which are supported by a transversing stud member 41 which rides upon a screw 48. Additional means for equalizing the relative effects of rods 45 and 46 may be employed and may comprise a plurality of adjusting nuts "49 carried by the member 41. Screw 48 may be supported at one end by a member 50, and screw '49 may be provided with a thumb adjustment 'member 5|.

In accordance with one feature of my invention, the input electrode means, and particularly probe 38 and linger 39, may be adjusted to match the resistive component of the impedance of the resonant region to the resistive component of the 'transmission line comprising conductors 36 and 31, and the plunger 44 may be adjusted to match the .reactive'component of the resonant. Vcavity or reglon to the reactive component of the transmission line. The effect of the adjustment of the plunger 44 will be explained hereinafter.

Where the device shown in Figs. 1 and 2 is to be employed as frequency changing or converting apparatus, I provide means for establishing within the resonant cavity an excitation of a frequency different from that of the input frequency, For example, this means may be a constant frequency exciting means energized from a local oscillator, and the circuit may be excited by means of a loop 52 forming an extension of a coaxial transmission line 53 comprising an outer conductor 54 and an inner conductor 55 energized from the local oscillator. The nature of conductors 54 and 55 and the configuration thereof may be such that the plunger 44 may be moved an appreciable dis` tance along "the longitudinal axis of the space resonant system. One way in which this result may be obtained is bypassing the concentric transmission line throughan opening in the member 41 and providing a sufficient length of transmission line between the local oscillator and member 41.

An output or utilization circuit 56, which is diagrammatically illustrated, may be connected between an externally accessible terminal of anode rod 33 and theouter cylinder 4 or the cathode part I9 of electric discharge device 5. Circuit 5S is shown as comprising a lumped inductance furnished by transformer 51 and a capacitance 58 which constitute an oscillatory or tank circuit tuned substantially to the intermediate frequency. It will be appreciated that I may employ a high frequency tuned circuit having a distributed inductance and capacitance Yas o will be evident in view of certain modifications of my invention described hereinafter. Furthermore, a by-pass capacitance 59 may be connected across the terminals of a direct current source 6.0 which impresses unidirectional voltage across the anode and cathode of discharge device E. Electrical energy at intermediate frequency may then be supplied to circuit 6I.

It may be helpful in the description of my invention to set forth rather generally certain fundamental aspects of my invention, particularly with reference to the tuning or matching feature. In Fig. 2a, there is shown an equivalent circuit representing the space resonant cavities or regions defined by cylinders 4 and 5. The distance between the input electrode means or probe 38 and finger 39, and grid part I8 may be presented by di, and the distance between the nger 39 and the end of the cavity dened by plunger 44 may be represented by the distance d2. The equivalent resistance and capacitance of the cathode-grid circuit of electric discharge device 6 are represented by the quantity ZR.

In order to obtain the maximum power transfer between electrical systems, the impedances of the transmitting and the utilization devices must be matched. That is, the impedance of one must be the complex conjugate of the impedance of the other. In other words, the resistive com,n ponents of the respective impedances must be equal and the reactive components of the respec- -tive impedances must be of equal magnitude but of opposite sign. Furthermore, consideringihe particular embodiment of myV invention illustrated in Fig.2', in order to obtain 'maximum power transfer the resistive component of the cav- -ity impedance must equal the' resistive component of the-transmission line impedance, and the rejspective. reactive components z must be of. equal magnitude and of opposite sign. Therefore, the net reactive component of the cathode-grid cavity must be equal t the reactive component of the transmission line bu-t of opposite sign thereto, the net cr effective reactive component of the cavity impedance being determined by both portions of the cathode-grid cavity, that is that part lying to the left of the input probe 38 and that part lying to the right of the input probe. As will be discussed presently, the net capacitive reactance of the cavity is controllable by the joint control of the input probe 38 and the plunger 44, the distance between the input probe 38 and the plunger 44 being characterized Vprimarily as a section of a short-circuited transmission line which, when the attenuation is considered negligible, may be viewed as a substantially pure reactance.

It can be shown that the impedance Za may be expressed as follows:

where Zo is the characteristic impedance of the involved d1 section of the cavity, that is, it is equal to where Z is the series impedance and Y is the parallel admittance per unit length, and a (propagation constant) is a complex quantity in the form of fr-l-j, where OC is the attenuation constant and ,8 is the phase constant.

If there is no attenuation within the system, that is if the resistance losses are negligible, fr becomes zero, and we may write: 1:713.

The impedance Zt, representing the impedance of the short-circuited section of the cavity looking to the right of the input electrode probe 38, may be represented as follows:

Z0 sinh cd2 '."w cosh d2 (2) If there is no attenuation, a is, therefore, equal to y' and the following relations are then readily obtainable:

Zb=Zo tallh idz (3) Zbzy'Zo tan IElda (4) It will be observed that the Equation 4 indicates that for a system of negligible attenuation, the impedance of the short-circuited section of the resonant cavity between probe 38 and plunger 44 may be represented as a pure reactance` Furthermore, Equation 1, defining Za, may be written as:

= .Z0 taub. Ude

Resisti ve Reactive Equation 7 consists now of a resistive component and a reactive component. If we assume that the reactivev component may always be compensated for, or neutralized by, the adjustment of plunger 44, a graphical representation of the real part of Za against the dimension d1 should give the location of the impedance matching points of the probe 38. By knowledge of the resistive component of the impedance of the transmission line comprising conductors 3B and 31, it is then possible to locate the position of the probe which establishes exact matching of the impedances of the cavity and transmission line.

In Fig. 4, the resistive component of Equation '7, represented by curve A, is plotted as a function of 01, where 01 is the equivalent electrical length of the cavity between discharge device 5 and input probe 38 expressed in electrical degrees based upon the phase constant or phase wave length ,8, where If the resistive component of the transmission line comprising conductors 36 and 31 is known, as for example being ohms, it will be observed that the impedance matching points cyclically occur at predetermined values of 01, such as at substantially 40 electrical degrees and 190 electrical degrees.

As stated above, the cavity impedance may be controlled by adjustment of plunger 44 to neutralize the reactive component of the cavity impedance as viewed from the input electrode means looking toward the electric discharge device 6. For example, if by the adjustment of the probe 33 to establish the desired correspondence between the resistive components of the line and the cavity, the net reactance of this section of the cavity is a capacitive reactance of a predetermined value, the plunger 44 may be adjusted so that the reactive component of the impedance looking from the probe 38 to the plunger 44 is an inductive reactance of corresponding value. Of course, the plunger 44 may be adjusted so that the cathode-grid cavity, as a whole, has a net reactive component equal in magnitude and opposite in sign to the reactive component of the line.

In accordance with a still further embodiment of my invention, the effective dimension de of the cavity is chosen so that the cavity is not only resonant to the frequency of the input excitation but is also resonant to the intermediate frequency; that is, the cavity is resonant to a resultant or difference of the input excitation frequency and the local oscillator frequency. More particularly, the cavity is adjusted by means of plunger 44 to constitute an odd multiple of quarter cycles of the input signal wave length. By the proper choice of dimension de, the cavity may also be made resonant to an odd multiple of quarter wave lengths of the intermediate frequency. It will be appreciated that various combinations of numbers of the respective quarter -wave lengths may be employed to carry out this joint resonant condition to both the input signal excitation and the intermediate frequency. For example, if ks represents the wave length of the input signal, and 7u is the wave length of the intermediate frequency, or vice versa, the following relationship establishes the joint resonant condition: l

i e 4 r.

where p is an odd integer, is an even integer,

.9 and de is the effective electrical length of the cavity taking into consideration end-effects.

It will be observed that in Equation 8 the effective electrical length de is employed which in the determination thereof necessitates the consideration of end-effects, and of course entails consideration of the effects due to the presence of the grid-cathode circuit of the electric discharge device 6 at one end of the cavity.

Even though in the arrangement illustrated in Figs. 1 and 2, the cavity is not designed to be resonant to the frequency of the local oscillator excitation, the frequency may be chosen so that even though the cavity is not resonant thereto appreciable local oscillator excitation will nevertheless be ,established therein.

'..In Fig. 5 there is illustrated another embodiment of my invention which is similar in construction to many features illustrated in the arrangements shown in Figs. 1 and 2 and corresponding elements have been assigned like reference numerals. In the arrangement of Fig. 5, a pair of space resonant cavities or regions are provided, one of which may be formed between the cylinders 4 and 5, and the second of which may =be formed by cylinder 5 and a conductive or metallic cylinder 62, which is also preferably constructed of copper or brass and which may be concentric with cylinders 4 and 5 and substantially surround the anode rod 33. Cylinder 62 may be flared at one end to afford a coupling between the anode extension 22 or the adapter 32, `but is not in physical Contact therewith due to the interposition of an insulator 63. By this means, the cylinder 62 is electively connected to the anode structure for high frequency currents but is insulated therefrom with respect to direct currents.` The region dened by cylinder 5 and cylinder 62 may be termed the grid-anode cavity which is tuned or resonant to the intermediate frequency. Suitable tuning means may be provided and may take the form of an adjustable conductive or metallic end wall, such as an annular plu-nger E4 which is in close engagement with the inner surface of cylinder 5 and the outer surface of cylinder 62 and may be positioned longitudinally by means of an adjusting or controlling rod B5. Energy may lbe extracted from the grid-anode cavity by any suitable means, and

for the purpose of illustrating such means I have shown a concentric transmission line 66 extending through end insulator 35 and terminated in a loop 5l extending into the grid-anode cavity.

l By virtue of the provision of the additional tuned cavity, it is possible in the arrangement of Fig. 5 to adjust the effective length of the cathode-grid cavity to be resonant to both the input signal frequency and the local oscillator frequency, and to obtain effective utilization of the intermediate frequency by virtue of the fact that the grid-anode cavity may be made resonant to the intermediate frequency by adjustment of plunger 64. Furthermore, in the arrangement of Fig. 5, by the adjustment of the input electrode means comprising probe 38, the impedance of the input cavity may be matched to the impedance of the transmission line comprising conductors 35 and 31, or matched to the impedance of other apparatus which may be connected to the input electrode means.

vReferring now to the arrangements shown in Figs. 6 and '7, I have there illustrated an embodiment of my invention as applied to a dielectric wave guide of the hollow-pipe type which may be constructed of conductive or metallic vdefining 10 walls or metal-like walls, such as metal sheathed walls. 'Prior to the description of the particular embodiments of the invention illustrated herein, it is believed that it may be helpful to review briefly certain fundamental characteristics of dielectric wave guides of the hollow-pipe type.

It is now quite generally appreciated that electromagnetic waves may be propagated through the interior of a metal or metal-like member or pipe of conductive material which contains a dielectric, if the frequency of the exciting electromagnetic waves is greater than a critical minimum frequency established principally by the transverse dimensions of the guide and the dielectric constant of the medium within the guide through which the waves are propagated. e

Dielectric wave guides of this nature may be employed for the transmission of electromagnetic waves of a variety of forms or character. These waves have been generally indicated heretofore as being of the E and H types. Subscripts, as indicated, Exam and Ham have been assigned to these waves in order to indicate the nature of the waves where n represents the order 0f the waves and m represents the mode of propagation. The order of the wave is determined by the manner in which field intensity varies circumferentially around the axis of the guide, whereas the mode is determined by the manner of the varia` tion with radial distance from the axis of the guide. The E type waves have both a longitudinal and a transverse component of electric field but only a transverse component of magnetic field.` On the other hand, the H type waves have both a longitudinal and a transverse component of magnetic field but only a transverse component of electric field. Although my invention is applicable for use in systems employing both the E and H types of waves, in describing the embodiment of my invention illustrated hereinafter particular reference will be made to the Hoi type wave. Furthermore, although my invention is also applicable to dielectric wave guides of the hollow-pipe type having various transverse configurations, the invention has been illustrated and described relative to a dielectric Wave guide having a rectangular crosssection.

For example, in a rectangular wave guide for an Hoi type wave, the phase constant g may be expressed as follows:

mamey-cri" where w, the angular velocity of the wave propagated through the medium of the guide, is equal to 21rf, where f is the frequency of the wave, p1. is the permeability of the medium, and e1 is the effective dielectric constant of the medium, a and b are the height and base, respectively, of the guide, the electric component of the eld being perpendicular to b, and n and m are the order and mode of the particular wave being transmitted through the guide.

The wave length Ag of the wave propagated through the guide may then be expressed as follows:

The total impedance of the rectangular guide may be dened as follows:

ZFT b (11) where ,ai is the permeability of the medium and where c is the velocity of light. If the guide l l impedance is constant along the guide, the wave will be propagated with no reflection. Io maintain this impedance constant for changes in guide dimensions a and b, one must have at any particular wave length the following relationship:

kg: constantE It (l2) It will be noted that in Equation 9 e1 is expressed as being the effective dielectric constant of the medium through which the waves are propagated. Inasmuch as I employ in several embodiments of my invention illustrated herein a region of charged electrical particles constituting an electric discharge path of an electric discharge device, in the determination of g and Ag it is necessary to take into consideration the effect of such a region of charged particles. Generally speaking, it may be said that the effective dielectric constant of the medium is the function of the difference of the dielectric constant of the medium with no charged particles present and a quantity which is directly proportional to the number of charged particles per unit volume, the square of the unit charge oi each particle, and inversely proportional to the mass of each charge and some function of the frequency.

Referring now more particularly to Figs. 6 and 7, I provide a dielectric wave guide of the hollowpipe type, such as a rectangular cross sectional wave guide having a base b and a height a. In this embodiment of my invention, it may be considered that I employ a section of a dielectric wave guide having dimensions such that the guide may be considered tuned or resonant to the frequency of the input excitation thereof, or resonant to the frequency of the electromagnetic waves established within the guide section. For example, I provide a rectangular wave guide having a conductive or metallic base plate B8, top plate 69 and side plates "IG and 'H which may be welded or soldered together. If desired, the dielectric vvave guide section may be terminated in conductive or metallic end walls 12 and i3.

I provide means for tuning the guide, that is controlling its effective length, and these means may comprise controllable or adjustable pistons Q 'I4 and 'i5 adjustable along the longitudinal axis of the guide. Means for establishing electromagnetic waves in response to a predetermined signal, and associated with the guide section, may comprise a concentric transmission line comprising a tubular conductor i6 and an inner conductor 'IT maintained in the desired spaced relation with respect to each other by means of an insulator i8. If desired, the conductor 11 may extend through the interior of the guide and be terminated in an adjustable line terminal 1S comprising a tubular member SEI which is conductively connected to the top plate G3 and has positioned therein an adjustable plunger 8| operable by means of ahandle 82. Bythis means,

I provide apparatus for controlling the imped-` ance of the wave guide section whereby the impedance thereof may be matched to that of the input electrode means.

Instead of employing separate input electrode means for establishing signal excitation within the wave guide, it will be appreciated that the left-hand end of the guide may be opened or terminated in a flared horn (not shown) or equivalent apparatus for establishing Within thel guide electromagnetic waves in response to space radiation.

A second excitation, such as an excitation of a frequency different from that of the signal excitation, may be established Within the guide by means of suitable electrode means, such as a concentric transmission line 83, which may extend through the right-hand end plate 13 and be supported and carried by piston 15 so that the piston is not impeded in its movement by the presence of the transmission line 83.

I provide within the dielectric wave guide section an electric discharge device 84 which may be similar in construction and arrangement to the electric discharge device 6 shown in detail in Fig. 3. The discharge device 84 may be located along the longitudinal axis of the guide and may be held in position by a pair of cylindrical adapters 85 and 86 which are electrically connected to the top plate 59 and the bottom plate 58, respectively. The inserted portions of adapters 85 and 86 may be fluted in order to afford suiiicient resilience to permit the insertion and removal of the device 84 and to maintain it in position after insertion. Cathode 81 and grid 88 of discharge device 34 are connected to oppositely disposed walls of the dielectric wave guide, that is, are connected to those walls to which the electric component of the electrostatic field is perpendicular. Adapters 85 and 86, therefore, may be employed as electrical connections for the cathode and the grid to the top and bottom plates of the wave guide section Anode 89 may be connected to an output or utilization circuit, such as a resonant intermediate frequency circuit which is diagrammatically illustrated as a circuit S0 having an inductance constituted by transformer 9! and a capacitance 92. Unidirectional voltage is applied across the anode 89 and cathode 84 in the manner illustrated and serves as a source of power for device 84.

I also provide means in apparatus of the nature disclosed for neutralizing the effect of the electric discharge device 84 within the guide. More particularly, I provide adjustable means, such as a metallic probe 83, extending into the wave guide and adjustable along the longitudinal axis thereof to neutralize any reflection incident to the presence of the discharge device. Probe 553 may extend through an opening 94 in the top plate 85 and may be supported by a metallic strap 95 to facilitate adjustment of the probe.

The operation of the embodiment of my invention illustrated in Figs. 6 and 7 may be employed as a frequency changer to supply to output circuit 9D electrical energy at intermediate frequency. If it be considered that the transmission line comprising conductors 'i6 and 11 is energized by an input signal of given frequency, a wave excitation will be established within the wave guide section. Furthermore, let it be assumed that transmission line 83 is excited at local oscillator frequency to establish within the guide an excitation of substantially constant frequency. By virtue of the interaction of these two excitations, the potential difference between the cathode 84 and grid 88 is modulated in accordance with a resultant which may be the difference of these two frequencies, thereby controlling or modulating the electron beam transmitted between cathode 8'! and anode 89 and supplying thereby to circuit 9D electrical energy at intermediate frequency.

The wave guide section may be tuned by means of pistons 14 and 15 to be resonant not only to '13 the frequency of the input signal furnished by conductors 16 and 11, but may also be made resonant to the intermediate frequency by the proper choice of the longitudinal dimension of the guide determined by the position of pistons 14 and 15 and by the choice of the proper number of odd quarter-wave lengths to satisfy the respective excitations.

Plunger 8| serves as an adjustable pure reactance element associated with the guide structure. Furthermore, the plunger 8| and piston 14 may be controlled jointly to match the impedance of the wave guide section to the impedance of the transmission line.

Referring more particularly to the features of the embodiment of my invention shown in Figs. 6 and 7, by nature of which the impedance of the guide may be matched to the impedance of the input electrode means comprising conductors 16 and 11, generally it may be stated that the resistive component of the impedance of the wave guide section may be controlled or adjusted by means of piston 14, land the resulting reactive component of impedance incident to the positioning of the piston 14 may be made equal to the reactive component of the transmission line by the adjustment of plunger 8|. Furthermore, if the resultant reactive component of the impedance after adjustment of piston 14 is inductive or capacitive, by the adjustment of piston 8| the net or elfective reactive component of the impedance may be controlled so that it is substantially equal in magnitude to the reactive component of the transmission line. By this means the impedance of the cavity may be matched to the impedance of the line.

The probe 93 is adjustable along the longitudinal axis of the guide to that position wherein it substantially neutralizes the reflection due to the presence f the electric discharge device 84. It may be considered, generallyy that the probe 93 produces an equal and opposite effect, so far as reflection is concerned, to that produced by discharge device 84.

In Fig. 8 I have illustrated a modification of the arrangement of my invention illustrated in Figs. 6 and 7 and corresponding elements have been assigned like reference numerals. In the arrangement of Figs. 8 and 9, the left-hand end of the wave guide section may be energized by space radiation or by input electrode means. The electric discharge path of the device 84 is modulated in accordance with a resultant of the input signal Iand the local oscillator signal furnished by transmission line 83 to establish a difference or intermediate frequency which is derived from the grid 88 and theV anode 89, and supplied to a tuned or resonant cavity or region dened by a conductive or metallic outer conductor 96 and an inner metallic conductor 01' cylinder 91. In effect, these conductors may be considered as a coaxial transmission line of tuneable character. Conductor 96 may be formed integral with an adapter 98 having a fluted section 99 which engages the grid 88 of the discharge device 84. It will be noted that grid 88 is conductively connected to the top plate 69 of the wave guide and that the cathode 81 is connected to the bottom plate 68. The inner conductor 91 may be flared at its lower portion to surround substantially the extension of anode 89 but not in physical contact therewith, thereby affording a high frequency electrical connection by virtue of the electrostatic coupling and at the same time aiording an arrangement where- 14 by unidirectional potential may be applied to anode 89 by means of a conductor |00 which may extend through the interior of conductor 91 and be electrically insulated and spaced therefrom. I also provide means for tuning the space resonant cavity defined between members 9| and 91, which may include an adjustable plunger |0| provided with an actuating rod |02. Plunger |0| may be provided with energy extracting means such as a loop |03 connected to a coaxial or concentric transmission line |04. In this manner, the intermediate frequency energy may be derived from the tuned or resonant cavity defined by devices 96 and 91.

The` embodiment of my invention illustrated in Fig. 8 also operates as a conversion appara-,- tus, such as a frequency changer, to supply to transmission line |04 electrical energy at inter-,- mediate frequency. The potential difference of the two excitations established by the input or intermediate frequency and the local oscillator frequency supplied through transmission line 83, modulates the electron beam transmitted between cathode 81 and anode 89 'to produce an intermediate frequency potential difference between grid 88 and anode 89 in this way exciting the resonant cavity defined by members 96 and 91. If desired, the arrangement of Fig. 8 may be adjusted so that the cavity produces a substantial standing wave due to the frequency of the electromagnetic waves propagated through the guide by virtue of the input excitation. Such an adjustment may be obtained by means of piston 15.

Figs. 9 and 10 illustrate a still further modification of my invention as applied to a dielectric wave guide, or a dielectric wave guide section comprising conductive or metal-like defining walls including a top plate |05, a base plate |06, and which may include a conductive or metallic end wall |01. Of course, the side dimensions of the guide may be established by metal-like or metallic side walls |08 and |09. In the arranges ment of Figs. 9 and 10, I employ an electric discharge device ||0 which is generally similar to the discharge device shown in Fig. 3, and which comprises only an anode and a cathode ||2. These members may be enclosed within an insulating cylinder, such as a vitreous cylinder, having features similar to the structure shown in Fig. 3. The discharge device ||0 may be maintained in position by adapters ||3 and ||4 simi-f lar in construction to adapters and 86 shown in Figs. 6 and 7. It will be noted that the anode and cathode are connected to oppositely disposed Walls of the dielectric wave guide in order to modulate the electric discharge or the electron beam transmitted therebetween in accordance with the potential difference between top plate |05 and base plate |00.

' In accordance with one feature of my invention shown in Figs. 9 and 10, the transverse dimension, particularly the width w, is chosen so that the guide section is resonant in the transverse direction to the intermediate frequency excitation established therein. This intermediate frequency, of course, may be determined by the input signal received at the left-hand end of the guide section and a substantially constant local oscillator frequency supplied by a concentric transmission line l5. More particularly, the transverse dimension w of the guide is chosen to be a multiple of a half-wave length of the intermediate frequency excitation, and the electric discharge device I0 is positioned within the guide so that itlies within the vicinity of the potential maximum of the transverse standing electromagnetic wave produced within the guide due to the intermediate frequency excitation. In 'this manner, the discharge device III) is positioned to utilize most effectively the potential variation due to 'the standing intermediate frequency wave.

In order to extract energy from the `guide at intermediate frequency, I may employ 4any suit'- able arrangement such as an output electrode means comprising a concentric transmission line IIG having a loop VI Il extending within the guide and preferably lying in a plane substantially transverse to the direction of propagation of `the signal electromagnetic wave through the guide. Of course, it is to be appreciated that instead of employing an output electrode means of the naf ture disclosed, I may employ another section of a dielectric wave guide having its principal axis substantially perpendicular to the longitudinal axis of the guide section illustrated, and having transverse dimensions such that the guide is tuned to or resonant to the intermediate frequency excitation.

The operation of the embodiment of my invena tion shown in Figs. 9 and 10 will now be explained. If it be considered that an electromagnetic wave of signal frequency enters the guide at the left-hand end and if it be further assumed that the input electrode means comprising concentric transmission line II5 is energized at adiiferent frequency, such as a constant dif ferent frequency, the potential difference between the anode III and cathode I I2 will be modulated in accordance with a resultant or difference frequency determined by these two waves, thereby controlling or modulating the electron beam transmitted between the anode and cathode. As a result thereof, there will be established within the guide an excitation of intermediate frequency; that is, there will be a wave of intermediate frequency within the vicinity of electric discharge device IIS. By virtue of the design of the transverse dimension of the guide to be resonant to the intermediate frequency, the intermediate frequency radiations will be localized within the vicinity of electric discharge device I I and may be readily extracted by loop I I'I.

As concerns the phenomenon which effects the localization of the resultant or dinerence frequency within the region surrounding the electric discharge device I IU by virtue of the design of the transverse dimensionsof the guide, the'guide may be 'made to propagate the two excitation frequencies longitudinally. Furthermore, the magnitude of the two input excitations and, hence, the difference frequency may be controlled so that the resultant or difference frequency is not propagated longitudinally; that is, the difference frequency is below the critical minimum frequency established by the cross-sectional dimensions.

In accordance with this feature of my invention, the transverse dimension uz of the guide may be established with consideration of the capacitance effects due to the discharge device III'I so that the dimension w is less or foreshortened, while nevertheless effecting the desired transverse tuning or resonance along the transverse dimension of the guide. Stated in other Words, the capacitance of the discharge device I I0 taken in conjunction with the distributed capacitance and inductance of the transverse dimension of the guide constitute a region tuned or substantially resonant to a resultant or difference of the two excitation frequencies.

' As pointed out above, for every dielectricwave all 'guide there is a critical or cut-off frequency below which electromagnetic waves are not propagated through the guide; that is, the waves are rapidly attenuated. One way in which my invention may be employed is by the choice of the transverse dimensions of the guide so that waves due tothe input signal are readily propagated through the guide, but which prohibit or limit appreciable propagation longitudinally through the guide of vthe intermediate frequency excitation. Consequently, this relationship will cause a concentration of the intermediate-frequency electromagnetic waves within the vicinity of the guide around the discharge device IIIl and along the transverse axis within this vicinity. Furthermore, the discharge device IIO, by virtue of its electric discharge path or electron beam, tends still further to reduce the effective dielectric constant of the guide within the vicinity thereof, thereby still further increasing the critical or cut-ofi` frequency inasmuch as the critical frequency fu is inversely proportional to the square root of the effective dielectric constant and may be dened as:

rat-.siempre where ,ai is the permeability of the medium, er is the effective dielectric constant, n and m are the order and mode of the particular wave being transmitted through the guide, a is the height of the guide and w is the width or basel While in the description of the space resonant cavities or regions of the various embodiments of my invention, the term conductive or metallic like wall has been employed, it will be appreciated that my invention is not limited to the utilization of pure metals as the defining wall material. For example, within the purview of my invention I may also employ any suitable conductive material which has an appreciable metallic or conductive component sufficient to main tain a localized region, or regions, of an electromagnetic field.

While I have shown and described my invention as applied to particular systemsand as embodying various devices diagrammatically shown, it will be Obvious to those skilled in the art that changes and modications may be made without departing from my invention, and I, therefore, aim in the appended claims to cover all Such changes and modifications as fall Within the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

l. High frequency apparatus comprising an electric discharge device including a plurality of electrodes comprising an anode, a cathode and a grid, a space resonant system associated with said device comprising a space resonant cavity connected to a pair of said electrodes, said cav-ity being excited in response to a predetermined signal, means connected to said cavity for establishing therein an excitation of a frequency different from the signal frequency, said cavity being resonant to both the signal frequency and the difference between the signal frequency and the last mentioned frequency, and utilization means connected to the remaining electrode.

2. High frequency apparatus comprising an electric discharge device including a plurality of electrodes comprising an anode, a cathode and a grid, a space resonant system associated with said device comprising a space resonant cavity connected to a pair of said electrodes, said cavity 17 being excited in response to a predetermined signal, means connected to said cavity for establishing therein an excitation of a frequency different from the signal frequency, said cavity being resonant to both the signal frequency and the difference between the signal frequency and said second frequency, and utilization means connected to the remaining electrode.

3. High frequency apparatus comprising an electric discharge device including a plurality of electrodes, a space resonant system associated with said device comprising a space resonant region connected to a pair of said electrodes, input means for establishing in said region an excitation of predetermined frequency, and means for establishing Within said region al second excitation of different predetermined frequency, said region being resonant to the frequency of an input signal applied to said electrode means and also resonant to a resultant of the input signal and said second excitation.

4. High frequency apparatus comprising an electric discharge device comprising a plurality of electrodes, a space resonant system associated With said device comprising a space resonant region connected to a pair of said electrodes, input meansconnected to said region, and means for establishing a constant frequency excitation within said region, said region being resonant to the frequency of an input signal applied to said *n input electrode means and also resonant to the difference between input signal frequency and said constant frequency,

5. High frequency apparatus comprising an electric discharge device including an anode, a

cathode and a grid, a space resonant cavity connected to said cathode and said grid, a transmission line, input electrode means connected between said transmission line and said cavity and I including a movable member for tuning the impedance of said cavity relative to the impedance of said line, means for establishing a constant frequency excitation in said cavity, said cavity being resonant to both the input frequency and the difference between said input frequency and said constant frequency, and output means connected to said anode.

6. High frequency apparatus comprising an electric discharge device having an anode, a cathode and a grid, a space resonant system associated with said device comprising a space resonant cavity connected to said cathode and said grid, a transmission line, input electrode means connected between said transmission line and said cavity and comprising an adjustable member for controlling the input impedance of said cavity relative to the impedance of said line, means for establishing a constant frequency excitation Within said cavity. Said cavity bung resonant to both the input frequency and the intermediate frequency.' and intermediate frequency output means connected tosaid anode.

'7. High frequency apparatus comprising an electric discharge device including a plurality of electrodes comprising an anode. a cathode and a grid. a space resonant system as-ociated with said device comprising a space resonant cavity connected to a pair of said electrodes, means for exciting said cavity in response to a predetermined signa-l, means connected to said cavity for establishing therein a substantially constant frequency excitation, said cavity being resonant to both the input signal frequency and the difference between the input signal frequency and said constant frequenc-y, and utilization means connected `to said anode.

8. High frequency apparatus comprising an electric discharge device having an anode, a cathode and a grid, a space resonant system associated with said device comprising a pair of substantially coaxial cylindrical conductive members connected to said cathode and grid and defining a space resonant region connected to the gridcathode circuit of said discharge device, and means comprising input electrode means extending through the outer cylindrical member and in engagement .with the inner member and adjustable longitudinally along said inner member to control the effective impedance of the grid-cathode region.

9. High frequency apparatus comprising an electric discharge device having an anode, a cathode and a grid, a space resonant system connected to said device comprising a space resonant region connected to said cathode and said grid and being defined by a pair of conductive members, means for establishing a constant frequency excitation in said region, a transmission line, input velectrode means connected between said transmission line and said region, and means for controlling said region to render it resonant to both inputfrequency excitation and intermediate frequency oscillation comprising means for controlling the axial dimension of said region.

l0. High frequency apparatus comprising an electric discharge device including a plurality of electrodes comprising an anode, a cathode and a grid, a space resonant system associated with said device comprising a space resonant -cavity connected to a pair of said electrodes, input means for exciting said cavity in response to a predetermined signal, and means for adjusting both th position of said input means and the dimensions of said cavity to control the effective impedance thereof.

11. High frequency apparatus comprising an electric discharge device including a plurality of eiectrodes'comprising an anode. a cathode and a grid, a space resonant system associated With said device comprising a snace resonant cavity connected to a pair of said electrodes, input means coupled to said cavity for exciting said cavity in response to a predetermined signal. and means for adjusting the position of said input means within said cavity and the longitudinal dimension of said cavity for controlling the resistive and reactive components of'the impedance of said cavity.

12. High frequency apparatus comprising an electric discharge device including a plurality of electrodes comprising an anode, a cathode and a grid. a space resonant system associated with said device comprising a space resonant cavity connected to a pair of said electrodes, input electrode means for exciting said cavity in response to a predetermined signal and comprising a member adjustable along the longitudinal axis of said cavity for controlling the resistive component of the impedance thereof. and utilization means connected to the remaining electrodes of said discharge device.

13. High frequency apparatus comprising an electric discharge device having an anode, a cathode and a grid, a space resonant system associated with said device comprising a space resonant regio-n definedv by a pair of conductive members connectedt-o said cathode and said grid, an adjustable metallic lend Wall'for said region, means for establishing' a .constant'frequency excitation in said region, input electrode means connected to a transmission line, and means for matching the impedance of Said 1@- gion to the impedance of said line comprising means for adjusting the positions of said input electrode means and said end Wall.

14. High frequency apparatus comprising an electric discharge device having an anode, a cathode and a grid, a space resonant system associated with said device comprising a space resonant region defined by a pair of conductive members connected to said cathode and said grid, input electrode means, a transmission line connected to said input electrode means, means for establishing a constant frequency excitation in said region, and means for matching the impedance of said region to the impedance of said line and comprising means for adjusting the position of said input electrode means and the dimensions of said region.

15. High frequency apparatus comprising an electric discharge device having an. anode, a cathode and a grid, a pair of coaxial concentric conductive cylinders defining a space resonant region which is connected to the cathode and grid of said device, output electrode means connected to said anode and cathode, a concentric trans-- mission line, and means comprising input electrode means having an electrode in contact with and slideable along the inner cylinder for tuning the ei'ective impedance of the grid-cathode region With respect to the impedance of said transmission line.

1G. High frequency apparatus comprising an electric discharge device having an anode, a cathode and a grid, a space resonant system associated ywith said device comprising a pair of conductive members for defining a space resonant region which is connected to the cathodegrid circuit of said device, means for controlling the dimensions of the grid-cathode region comprising a positionablc end metallic wall, output means connected to said anode and said cathode, and input electrode means in engagement with one of the members which denne the grid-cathode region comprising an adjustable electrode the position of which determines the elective impedance of the grid-cathode region as viewed from the input electrode means.

17. High frequency apparatus comprising an electric discharge device having an anode, a cathode and a grid, a space resonant system associated with said device comprising a pair of substantially coaxial members which denne a space resonant region which is connected to the cathode-grid circuit of said discharge device, metallic end Wall mea-ns for deiining an end boundary of the grid-cathode region and being adjustable to control the eilective electrical length thereof, and input electrode means comprising an adjustable member in physical contact With the inner member which is connected to said grid for controlling the eiective impedance of the grid-cathode region as viewed from the input electrode means.

18. High frequency apparatus comprising an electric discharge device having an anode, a cathode and a grid, and a space resonant system associated with said device comprising a pair ci substantially coaxial members defining a space resonant region which is connected to the cathode-grid circuit of said discharge device, means comprising an adjustable metallic end Wall constituting one boundary of the grid-cathode region for controlling the effective electrical length thereof, a concentric transmission line, and input electrode means connected to said transmi. sion line and comprising a member adjustabe along the length of the inner metallic member connected to said grid so that the impedance of said grid-cathode region may be matched to the impedance of said line.

i9. High frequency conversion apparatus ccmprising an electric discharge device having an anode, a. cathode and a a space resonant structure associated with sain de 'ce and cornprising a pair of substantif l coaxial m te defining a space resonant -egion which nected to the cathode-grid circuit of said device, means comprising a metallic end Wall for coz"- trolling the effective length of the grid-cathode region, electrode means energized from a local oscillator for exciting grid-cathode region mission line, input electrode means connected to said transmission line and comprising a member in physical Contact 'with and adjustable along the inner metallic member connected to said grid for controlling the effective impedance ci the grid-cathode region, and intermediate frequency output means connected to said anode.

2i). High frequency conversion apparatus comprising an electric discharge device having an anode, a cathode and a grid, space resonant structure associated with said device and comprising a pair of concentric members defining a space resonant region which is connected to the cathode-grid circuit of said discharge device, means comprising an adjustable metallic end wall structure for controlling the eective electrical length i the grid-cathode region, electrode means energized from a local oscillator for exciting the gridcathode region at a predetermined frequency, a concentric transmission line, input electrode means comprising a, member extending into the grid-cathode region and in physical contact with and adjustable along the axial dimension of 'the inner member connected to said grid for matching the impedance of the grid-cathode re-"ion to the impedance oi said line, and intermediate frequency output means connected to said anode and said cathode.

2i. High frequency conversion apparatus comprising an electric discharge device having an anode, a cathode and a grid, a space resonant system associated with said device comprising a of space resonant cavities defined by three substantially concentric conductive members, the outer and inter .crediate members being connected to said cathode and said grid respectively, and said intermediate and inner members being connected to said grid and said anode respectively, means for tuning the cathode-grid. cavity, and means for tuninsr the grid-anode cavity to be nant to the diierence frequency of the excitations established Within the cathode-grid cavity.

22. High frequency conversion apparatus comprising an electric discharge device having an anode, a cathode and a grid, a space resonant system associated with said device comprising three substantially concentric conductive members, the outer member and the intermediate member being connected to the cathode and grid, and said intermediate member and the inner member' being connected to said grid and said anode. respectively, means for tuning the cathodegrid cavity to be substantially resonant to an input signal of predetermined frequency, means for exciting said cathode-grid cavity at a substan- 21 tially constant frequency, and means for tuning the grid-anode cavity to be resonant to the intermediate frequency.

23. High frequency apparatus comprising an electric discharge device having an anode, a cathode and a grid, and a space resonant system associated with said device comprising three substantially concentric members for defining two space resonant regions one of which is connected to the cathode and grid and the other of which is connected to the gridA and the anode, means for exciting the cathode-grid region Aat a substantially constant frequency, and input means for exciting said cathode-grid region in response to a predetermined signal, said cathode-grid region being tuned substantially to the frequency of said input signal and said grid-anode region being tuned substantially to the intermediate frequency.

24. High frequency apparatus comprising a plurality of electrodes including an anode, a cathode and a grid, a space resonant system associated with said device and comprising a pair of space resonant cavities one of which is connected to said cathode and said grid and the other of which is connected to said grid and said anode, input electrode means connected to the cathodegrid cavity, output electrode means connected to said grid-anode cavity, electrode means for establishing an excitation of substantially constant frequency in said cathode-grid cavity, said cathode-grid cavity being tuned to both the frequency of the input excitation and said constant frequency and said grid-anode cavity being tuned to the intermediate frequency.

25. High frequency conversion apparatus comprising an electric discharge device having an anode, a cathode and agrid, a space resonant system associated with said device comprising three substantially coaxial members for defining two space resonant regions one of which is connected to said cathode and grid and the other of which is connected to said grid and said anode, input electrode means for exciting the cathodegrid cavity in response to a predetermined signal, means for exciting said cathode-grid region at a substantially constant frequency, said cathodegrid region being resonant to both the frequency of the input signal and said constant frequency excitation and said grid-anode region being resonant to the intermediate frequency, and output electrode means associated with said grid-anode region.

26. High frequency apparatus comprising an electric discharge device having an anode, a cathode and a grid, a space resonant system associated with said device comprising a pair of space resonant regions defined by a pair of coaxial members, one of said regions being connected to said cathode and said grid and the other region being connected to said grid and said anode, a transmission line, input electrode means connected between said transmission line and the cathode-grid cavity, and means for tuning said cathode-grid cavity comprising means for adjusting the effective position of said input electrode means and the axial dimension of said region.

27. In combination, a dielectric wave guide of the hollow-pipe type comprising a plurality of defining walls, said wave guide having an appreciable longitudinal dimension along which may be. propagated electromagnetic waves of a frequency Ygreater than the cut-off frequency of the Vwave guide established principally by the transverse dimensions thereof, meansfor establishing Within said guide an electromagnetic wave of a frequency greater than said cut-off frequency, an electric discharge device including a pair of electrodes connected between oppositely disposed walls of said guide and producing an electric discharge path, means for establishing within said guide an electromagnetic wave of a second predetermined frequency greater than the cut-off frequency, the transverse dimension of said guide being such that the guide is tuned substantially to the difference between the rst mentioned and the second mentioned frequencies thereby modulating said electric discharge path in accordance with said difference frequency to effect the establishment along the transverse dimension of said guide of an electromagnetic field of difference frequency, and output electrode means for extracting energy at the difference frequency.

28. In combination, a dielectric wave guide of the hollow-pipe type comprising a plurality of defining walls, said wave guide having an appreciable longitudinal dimension and transverse dimensions to effect the dielectric propagation of electromagnetic waves above a predetermined frequency along the longitudinal axis, means for establishing within said guide an electromagnetic wave of a frequency greater than said predetermined frequency, second means for establishing within said guide an electromagnetic wave of second predetermined frequency, an electric discharge device including an anode and a cathode positioned within said guide, said anode and said cathode being conductively connected to oppositely disposed walls of said guide to modulate the electric discharge path in accordance with the difference of the first mentioned predetermined frequency and the second predetermined frequency, the transverse dimension of said guide being an integral multiple of a half-wave length of the difference frequency and said electric discharge device being positioned within the vicinity of the potential maximum of the transversely propagated difference frequency wave, and output electrode means for extracting energy from said difference frequency wave.

29. In combination, a section of a dielectric wave guide of the hollow-pipe type comprising a conductive dening member capable of sustaining electromagnetic waves of a frequency greater than a critical minimum frequency, said section being excited by an incoming signal, an electric discharge device comprising a pair of enclosed electrodes connected to points Within said section varying in potential in accordance with thev electric component of the eld incident to said waves, means for establishing within said section an excitation of a frequency different from the input signal frequency, said section being resonant to both the signal frequency and the intermediate frequency excitations, and circuit means connected to said discharge device.

30. High frequency conversion apparatus comprising a section of a dielectric wave guide including a conductive defining member capable of sustaining electromagnetic waves of a frequency greater than a critical minimum frequency, said section being excited by an input signal having a frequency greater than said critical minimum frequency, an electric discharge device including a plurality of enclosed electrodes comprising an anode, a cathode and a grid, said cathode and said-grid being connected-to points of said member in order to utilize the potential difference incident to the electromagnetic field within said guide, means for establishing Within said guide a second excitation of a frequency different from the input excitation frequency, said section being resonant to both the signal frequency and the intermediate `frequency eX- citations, and intermediate frequency circuit means connected to said anode.

3l. In combination, a sect-ion of a dielectric wave guide of the hollow-pipe type compr: ing a conduct-ive defining member through which electromagnetic waves of a predetermined frequency greater than critical minimum frequency mas7 be transmitted, said section being resonant to an input signal having a frequency greater than said minimum frequency, means for establishing within said guide electromagnetic Wave cf substantially constant frequency the value of which is different from that of the input frequency, an electric discharge device enclosed within said guide and comprising a plurality of enclosed electrodes including an anode= a cathode and a grid, said cathode and said grid being connected to oppositely disposed points of said guide member, and circuit means connected to said anode.

32. In combination, a section of a' dielectric Wave guide of the hollow-pipe type comprising a conductive defining member through which electromagnetic Waves of a predetermined frequency greater than a critical minimum frequency may be transmitted, said section being resonant to electromagnetic Waves of a predetermined frequency established therein, the resonance frequency being determined principally by the longitudinal dimension of said guide section, means for establishing Within said guide an excitation of a frequency diiferent from said frequency, an electric discharge device enclosed within said guide and comprising a plurality of enclosed electrodes including an anode, a cathode and a grid, said anode and said cathode being connected to oppositely disposed points of said guide to utilize the potential difference incident to the electric component of the electromagnetic field therein, and circuit means connected to said anode.

33. In combination, a section of a dielectric wave guide of the hollow-pipe type comprising a conductive defining member through which electromagnetic `vvaves of a predetermined frequency greater than a critical minimum frequency may be transmitted, said section being resonant to an input signal having a frequency greater than said minimum frequency, means for establishing Within said guide an electromagnetic Wave of substantially constant frequency the value of which is different from that of the last mentioned frequency, means for tuning said guide section, an electric discharge device enclosed within said guide comprising a plurality of enclosed electrodes including an anode, a cathode and a grid, said cathode and said grid being connected to oppositely disposed points of said guide section, and means resonant to the difference in frequency between said input signal and said constant frequency connected to said anode, said difference frequency being less than said critical minimum frequency.

34. In combination, a dielectric Wave gudecf the hollow-pipe type comprising a conductive dening member through which electromagnetic Waves of a predetermined frequency greater than a critical minimum frequency may be transmitted, means for establishing Within said guide an excitation of a frequency different from that of the rst mentioned frequency, means for tuning said wave guide to be resonant to the frequency of an incoming signal, an electric discharge device enclosed Within said guide and comprising a plurality of enclosed electrodes including an anode, a cathode and a grid, said cathode and said grid being connected to oppositely disposed points of said guide, and tuned circuit means connected to said anode.

35. In combination, a section of a dielectric wave guide of the hollow-pipe type comprising a conductive dening member through which electromagnetic waves may be propagated, means for establishing within said guide an excitation of a frequency different from that of an incoming signal, said section being tuned to both the frequency of the incoming signal and the intermediate frequency, an electric discharge device comprising a pair of enclosed electrodes which are connected to oppositely disposed transverse points of said member, and circuit means connected to said discharge device.

36. High frequency conversion apparatus comprising a section of a dielectric wave guide including a conductive defining member capable of sustaining electromagnetic waves of a frequency greater than a critical minimum frequency, means for establishing within said section an eX- citation of a frequency different from that of an incoming signal, an electric discharge device comprising a pair of enclosed electrodes connected to points within said section lying substantially in the plane of the electric component of the field incident to the Waves Within said section, said section being resonant to both the incoming signal and the intermediate frequency excitations, and circuit means connected to said discharge device.

37. High frequency conversion apparatus compiising a section of a dielectric Wave guide comprising conductive defining Walls, input electrode means, means for tuning said section to be resonant to the frequency of the excitation supplied oy said input electrode means, second input electrode means, an electric discharge device enclosed within said guide and comprising a plurality of enclosed electrodes including an anode, a cathode and a grid, said cathode and said grid beingr connected to oppositely disposed Walls of said guide, and tuned circuit means connected to said anode.

38. High frequency apparatus comprising a dielectric Wave guide comprising conductive Wall members, means for tuning said guide to be resonant to a predetermined frequency, means for exciting said guide at said frequency, means Within said guide comprising an electric discharge device comprlsing a plurality of enclosed electrodes including an anode, a cathode and a grid, means for conductively connecting said cathode and said grid to oppositely disposed walls of said guide, input electrode means connected to said guide, and intermediate frequency utilization means connected to said anode.

39. High frequency conversion apparatus comprising a dielectric Wave guide having conductive dening Walls, means for tuning said guide, input electrode means, second input electrode means, an electric discharge device enclosed Within said guide and comprising `a plurality of elecrodes includin an anode, a cathode and a grid, said cathode and said grid being connected to Oppositely disposed Walls of said guide, and utilization means connected to said anode.

e0.l High frequency conversion apparatus comprising a section of a dielectric Wave guide dened by conductive walls, input electrode means connected tosaid guide, second input electrode means for establishing an excitation of predetermined substantially constant frequency within said guide, an electric discharge device enclosed within said guide and including a plurality of enclosed electrodes comprising an anode, a cathode and a grid, said cathode and said grid being connected to oppositely disposed walls of said grid, andintermediate frequency utilization means connected to said anode.

41. Frequency changing means comprising a section of a dielectric wave guidecomprising conductive defining walls, input electrode means, means for tuning said guide to be resonant to the frequency of the excitation supplied by said input electrode means, an electric discharge device enclosed within said guide and comprising a, plurality of enclosed electrodes including an anode, a cathode and a grid, said cathode and said grid being connected to oppositely disposed Walls of said guide, second input electrode means for establishing within said guide an excitation of substantially constant frequency, and tuned circuit means connected to said anode for supplying an electrical quantity responsive to the diiierence between the frequencies of the input electrode excitation and said second electrode excitation.

42. High frequency apparatus comprising a dielectric Wave guide including conductive defining walls, input electrode means connected to said guide, means for tuning said guide to be responsive to the excitation supplied by said input electrode means, an electric discharge device comprising a plurality of enclosed electrodes including an anode, a cathode and a grid, two of said electrodes being connected to oppositely disposed walls of said guide, utilization means connected to the remaining electrode, and means positioned within said guide for neutralizing the reflection incident to thepresence of the electric discharge device therein.

43. High frequency apparatus comprising a dielectric wave guide including a plurality of conductive defining walls, input electrode means connected to said guide, means for tuning said guide to be resonant to the frequency supplied by said input electrode means, an electric discharge device comprising a plurality of enclosed electrodes including an anode, a cathode and a grid, two of said electrodes being connected to oppositely disposed walls of said guide, the remaining electrode being connected to a utilization circuit, and means positioned within said guide intermediate said input electrode means and said electric discharge device for neutralizing the reflection incident to the presence of said discharge device within said guide.

-guide to be resonant to the frequency of the excitation supplied by said input electrode means,

an electric discharge device comprising a plulrality of enclosed electrodes including an anode,

a cathode and a grid, two of said electrodes being connected to oppositely disposed walls of said guide, a utilization circuit connected to the reand said discharge device for substantially neutralizing the reflection of the electromagnetic waves incident to the presence of said discharge device.

45. In combination, a dielectric wave guide comprising a plurality of conductive dening Walls, input electrode means connected to said guide, end wall adjusting means for tuning said guide to be resonant to the frequency of the excitation supplied by said input electrode means, an electric discharge device positioned within said guide comprising an anode, a cathode and a grid, means for connecting said cathode and said grid to oppositely disposed walls of said guide to modulate an electric discharge between said anode and said cathode in accordance with the magnitude of the electromagnetic waves within said guide, utilization circuit means connected to said anode, and means for neutralizing the reiiection incident to the presence of the electric discharge device comprising a longitudinally adjustable probe extending into said guide and positioned between said input electrode means and said electric discharge device.

46. In combination, a dielectric Wave guide of the hollow-pipe type comprising a plurality of conductive defining walls, input electrode means connected to said guide, means for tuning said guide to be substantially resonant to the frequency of the excitation supplied by said input electrode means, second input electrode means for establishing a second excitation of diierent predetermined frequency, an electric discharge device enclosed within said guide and comprising a plurality of enclosed electrodes including an anode, a cathode and a grid, means for connecting said cathode and said grid to walls of said guide in order to modulate an electric discharge transmitted between said anode and said cathode in accordance with a resultant of the excitations produced by the rst mentioned input electrode means and said second input electrode means, and utilization means connected to said anode.

47. In combination, a dielectric wave guide of the hollow-pipe type comprising a plurality of conductive defining walls, input electrode means connected to said guide, means for tuning said guide to be substantially resonant to the frequency of the excitation supplied by said input Velectrode means, second input electrode means for establishing a second excitation of different predetermined frequency, an electric discharge device enclosed Within said guide and comprising a plurality of enclosed electrodes including an anode, a cathode and a grid, means for connecting said cathode and said grid to Walls of said guide in order to modulate an electric discharge transmitted between said anode and said cathode in accordance with a resultant of the excitations produced by the rst mentioned input electrode means and said second input electrode means, and intermediate frequency means comprising a circuit tuned substantially to the intermediate frequency connected to said anode.

48. In combination, a dielectric Wave guide of the hollow-pipe type comprising a plurality of conductive defining walls through which electromagnetic waves of a frequency greater than a critical minimum frequency are transmitted, an end deiining wall for said guide, means for estab- I lishing within said guide an excitation of a freand a grid, means for connecting said cathode and said grid to oppositely disposed walls of said guide for modulating an electric discharge transmitted between said anode and said cathode in accordance with a resultant of the electromagnetic waves within said guide, means for impressing a unidirectional voltage across said anode and said cathode, tuned high frequency transmission line means responsive to the variations ef potential between said anode and said grid, and output electrode means connected to the last mentioned means.

In combination, a dielectric wave guide of the hollow-pipe type comprising a plurality of defining walls within which electromagnetic waves ef predetermined frequency are transmitted, an end metallic defining wall for said guide, means for establishing Within said guide a second excitation of frequency different from the first mentioned frequency, an electric discharge device enclosed within said guide and comprising an anode, a cathode and a grid, means for connecting said cathode and said grid to oppesitely disposed walls of said guide to modulate an electric discharge transmitted between said anode and said cathode in accordance with a resultant of the first mentioned and second excitations, a circuit tuned substantially to said resultant frequency comprisingr a coaxial transmission line including inner and outer metallic conducting members one of which is conductively connected to said grid and the other of which is electrostatically coupled to said anode, means for impressing a unidirectional potential across said anode and said cathode, and output electrode means responsive to the electromagnetic waves within the region defined between said inner and said outer members.

e. In combination, a dielectric Wave guide comprising a plurality ef defining walls and having longitudinal dimension substantially greater than the transverse dimension, said dielectric wave guide being adapted for the transmission longitudinally therethrough of electromagnetic waves of a frequency greater than the critical minimum frequency established by the transverse dimension of said guide, an end defining wall for said guide, means for establishing within said guide an excitation of a frequency different than the first mentioned frequency, an electric discharge device comprising a pair of electrodes which are connected to oppositely disposed walls of said guide for controlling the potential difference between said oppositely disposed walls in accordance with the resultant of the first mentioned and second mentioned frequencies, and electrode means lying in a plane substantially transverse to the longitudinal axis of said guide and responsive to transverse electromagnetic radiation within said guide, said transverse dimension of said guide being such that said guide is tuned substantially to said diiference frequency.

51. In combination, a dielectric wave guide of the hollow-pipe type comprising a plurality of defining walls, said wave guide having an appreciable longitudinal dimension for the transmission of electromagnetic waves of a given frequency longitudinally therethrough, means for establishing within said guide an electromagnetic wave of second predetermined frequency, an electric discharge device including a pair of electrodes comprising an anode and a cathode connected to oppositely disposed walls of said guide for modulating the potential difference between said oppositely disposed walls in accordance with 28 the difference between the first mentioned and second mentioned frequencies, the transverse dimension of said guide being such that the guide is resonant to the difference frequency, andeutput electrode means lying in a plane substantially transverse to the longitudinal axis of said guide.

52. In a dielectric wave f 1dde oi the hollowpipe type, the method oi frequency changing which comprises 'transmit .ng an electromagnetic Wave longitudinally' through said guide, establishing an excitation having a frequency different than the first mentioned wave, modulating the potential difference etween oppositely disposed walls of said in accordance with the resultant of the first mentioned wave and said second exci ien te prod ce a transversely propagated electromagnetic wave, and deriving energy from said guide in response to +he transversely propagated eiectromagnetie waves.

53. l'n coiniinatien, a dielectric wave guide of the hollow-pipe type comprising a conductive deiining member, said wave guide having an appreciable longitudinal dimension along which may be propagated electromagnetic waves of a frequency greater than the cut-olf frequency of said guide established by the transverse dimensions theeof, wave guide being excited in response to a signal of predetermined frequency greatel1 than said cut-off frequency, an electric ischarge device positioned within said guide and including a pair of enclosed electrodes connected to eppositely disposed points of said member for producing an electric discharge therebetween, means for establishing within said guide an electromagnetic wave oi second predetermined frequency greater than the cut-off frequency, the transverse dimension of said guide being such that the guide is tuned substantially to the difference between the first mentioned and the second mentioned frequencies thereby modulating the discharge between said anode and said cathode in accordance with the difference frequency to effect the establishment along the transverse dimension of said guide of an electromagnetic field of difference frequency, and means for eX- tracting energy at said difference fe-Oluency.

5L, ln combination, a dielectric wave guide of the hollow-pipe 'type comprising a conductive defining member, said guide having an appreciable longitudinal dimension along which may be propaga-ted electromagnetic waves of a frequency greater than the cut-oil frequency of said guide established principally by the transverse dimension thereof, said guide being excited by an electromagnetic wave having a frequency greater than the cut-off frequency, an electric discharge device positioned within said guide and including an enclosed anode and cathode connected between oppositely disposed points of said member and producing therebetween an electric discharge, means for establishing within said guide an electromagnetic wave of substantially constant frequency greater than the cut-off frequency, the transverse dimension of said guide being such that the guide is tuned substantially to the difference between the signal frequency and said constant frequency thereby modulating said electric discharge in accordance with the difference frequency to effect the establishment along the longitudinal axis of said guide of an electromagnetic ieid of difference frequency, and means for extracting energy from said guide at said difference frequency, said difference frequency being less than said cut-off frequency thereby effecting the localization of said differ- 29 l ence frequency Within the vicinity of said discharge device.

55. In combination, a section of a dielectric Wave guide of the hollow-pipe type comprising a conductive defining member capable of supporting electromagnetic Waves, an electric discharge device comprising a plurality of enclosed electrodes connected to points within said section varying in potential in accordance With the electric component of the eld incident to said Waves, input electrode means for exciting said section, means for controlling the dimension of said section to control the resistive component of the impedance thereof, and means for adjusting the position of said input electrode means for controlling the reactive component of the impedance of said section.

56. In combination, a section of a dielectric Wave guide of the hollow-pipe type comprising a conductive defining member, an electric discharge device positioned Within said section and comprising a pair of enclosed electrodes connected to points oppostely disposed within said section, a transmission line, input electrode means connected between said transmission line and said section, and means for controlling the impedance of said section relative to the impedance of said line and comprising means for controlling the conguration of said section and means for adjusting the position of said input electrode means.

57. In combination, a section of a dielectric Wave guide of the hollow-pipe type comprising a conductive deiining member, an electric discharge device positioned within said section and comprising a pair of enclosed electrodes connected to points cpp-ositely disposed Within said section, a transmission line, input electrode means connected between said transmission line and said section, and means for matching the impedance of said section to the impedance of said line comprising means for controlling the longitudinal dimension of said section and means for adjusting the position of said input electrode means for controlling the net reactive component of the section impedance.

58. In combination, a dielectric wave guide of the hollow-pipe type excited at a frequency above the cut-ofi frequency, means for establishing Within said guide an excitation of a frequency different from the rst mentioned frequency, an electric discharge device positioned in said guide and constituting with the distributed inductance and capacitance of the transverse dimensions of the guide a region substantially resonant to the resultant of the rst mentioned and said last mentioned frequencies.

59. In combination, a dielectric wave guide of the hollow-pipe type excited at a frequency above the cut-ofi frequency, means for establishing a second excitation Within said guide of a frequency different from the rst mentioned frequency, and an electric discharge device positioned within said guide, the capacitance of said discharge device constituting with the distributed inductance and capacitance of the transverse dimensions of the guide a region tuned substantially to a resultant of the rst mentioned and said second excitation frequencies.

60. In combination, a dielectric Wave guide of the hollow-pipe type having therein an excitation of a predetermined frequency above the cut-off frequency, means for establishing Within said guide a second excitation of a frequency different from the first mentioned frequency, and an electric discharge device positioned within said guide, the capacitance of said discharge device constituting with the distributed inductance and capacitance of the transverse dimension of said guide a region substantially resonant to a dfference of the first mentioned and said second excitation frequencies.

61. A high frequency system `comprising, a closed conductive member dening a space resonant cavity, input electrode means connected to said cavity, a transmission line connected to said input electrode means, and means for matching the impedance of said cavity to the impedance of said line comprising means for adjusting the position of said input electrode means in said cavity to control the resistance component of said cavity impedance, and means for adjusting the dimensions of said cavity to control the reactive component of said impedance.

FRANCIS M. BAILEY.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,106,769 Southworth Feb. 1, 1938 2,253,589 Southworth Aug. 26J 1941 2,169,305 Tuniek Aug. 15, 1939 2,283,895 Mouromtsei May 19, 1942 

